Observations of a radio-bright, X-ray obscured GRS 1915+105
Date Issued
2021
Author(s)
•
Kajava, J. J. E.
•
Giustini, M.
•
Williams, D. R. A.
•
•
Fender, R.
•
Green, D. A.
•
Heywood, I.
•
Rhodes, L.
•
•
Sivakoff, G.
•
Woudt, P. A.
Abstract
The Galactic black hole transient GRS 1915+105 is famous for its markedly variable X-ray and radio behaviour, and for being the archetypal galactic source of relativistic jets. It entered an X-ray outburst in 1992 and has been active ever since. Since 2018 GRS 1915+105 has declined into an extended low-flux X-ray plateau, occasionally interrupted by multiwavelength flares. Here, we report the radio and X-ray properties of GRS 1915+105 collected in this new phase, and compare the recent data to historic observations. We find that while the X-ray emission remained unprecedentedly low for most of the time following the decline in 2018, the radio emission shows a clear mode change half way through the extended X-ray plateau in 2019 June: from low flux (∼3 mJy) and limited variability, to marked flaring with fluxes two orders of magnitude larger. GRS 1915+105 appears to have entered a low-luminosity canonical hard state, and then transitioned to an unusual accretion phase, characterized by heavy X-ray absorption/obscuration. Hence, we argue that a local absorber hides from the observer the accretion processes feeding the variable jet responsible for the radio flaring. The radio-X-ray correlation suggests that the current low X-ray flux state may be a signature of a super-Eddington state akin to the X-ray binaries SS433 or V404 Cyg.
Volume
503
Issue
1
Start page
152
Issn Identifier
0035-8711
Ads BibCode
2021MNRAS.503..152M
Rights
open.access
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